As shown in FIGS. 6 and 7, a first conventional embodiment of a light source and a surface emitting device includes a wide bottom reflection sheet 120 arranged at a liquid crystal display section of a cellular phone or a digital camera, a light guide plate 121 formed on the top surface of the bottom reflection sheet 120 and protrudes at one end from one end of the bottom reflection sheet 120, a light source 122 arranged to face the side surface of the light guide plate 121 and a top reflection sheet 127 covering the end of the light emitting surface of the light guide plate 121 and the light source 122 from above.
The light source 122 includes a narrow flat flexible plate 123 which overlaps with the protruding end of the light guide plate 121 and serves as a wiring board, horizontally oriented rectangular parallelpiped cases 124 which are arranged on the flexible substrate 123 to be close to the side surface of the light guide plate 121, light emitting elements (not shown) contained in the cases 124, respectively, and transparent, light-transmissive resin seal layers 125 that fill the cases 124, respectively.
In each of the cases 124, a face parallel to the side surface of the light guide plate 121, i.e., a light exit face has an opening. A resin sealant is introduced from the opening into the case 124 to close the opening. At the side plane of each of the cases 124, a lead terminal 126 for electrical conduction of the light emitting elements is drawn out and electrically connected to a wiring pattern on the flexible substrate 123 by soldering.
Light from the light emitting elements comes out of the light exit faces of the cases 124 and enters the light guide plate 121. A portion of light leaking from the top and bottom planes of the cases 124 is reflected from the top reflection sheet 127 to be incident on the light guide plate 121. As the light is not wasted, the luminance of the light emitting surface of the light guide plate 121 improves.
A second conventional embodiment of the surface emitting device is shown in FIGS. 8 and 9. In the surface emitting device, recesses 131 for containing light emitting elements 132, respectively, are formed at the end of a light guide plate 130. Each of the light emitting elements 132 is mounted on a narrow flat flexible substrate 133 serving as a wiring board and placed in the recess 131 such that the light exit face of the light emitting element 132 faces the same direction as the light emitting surface of the light guide plane 130. The light emitting surface of the light guide plate 130 faces a liquid crystal display panel depicted in the figure by alternate long and short dashed lines. A resin seal layer 134 is formed in each of the recesses 131 of the light guide plate 130 to fill the space around the light emitting element 132. A top reflection sheet 135 having the same width as the recesses 131 is formed on the end of the light emitting surface of the light guide plate 130 and a dot pattern 136 is formed on the bottom surface of the light guide plate 130 except the recesses 131.
A portion of light emitted from the light emitting elements 132 is reflected from the top reflection sheet 135 to the inside of the light guide plate 130. In the light guide plate 130, light directly entered from the light emitting element 132 and light reflected from the top reflection sheet 135 are diffused by the dot pattern 136. Accordingly, the light emitting surface of the light guide plate 130 achieves light emission with uniform luminance. The structure of the conventional light emitting element is disclosed, for example, by Japanese Unexamined Patent Publication No. 2001-67917, pp. 3-6 and FIGS. 2 and 3.